A. Field of the Invention
The present invention relates to the lighting of relatively large areas or targets, and in particular, to the use of high intensity light sources to light such areas or targets in a highly efficient yet highly controllable manner.
B. Problems in the Art
There are many instances where highly efficient and highly controllable high intensity lighting could be advantageous. There are many known methods of high intensity lighting. Most utilize some sort of an arc lamp of relatively high wattage and a reflector system that attempts to direct part of the light from the arc lamp to a target area. An example is the widely used axially mounted arc lamp in a bowl-shaped hemispherical reflector. This type of known lighting is described in detail in U.S. Pat. Nos. 5,343,374 and 5,337,221.
Although this type of fixture can produce a relatively high intensity, controlled and concentrated beam, the nature of the fixture presents some difficulties with respect to efficiency and control. Such fixtures normally are elevated at least several tens of feet and then aimed towards the target location. Because the reflector is symmetrical, some light falls directly on the target area but other light falls outside the target area. Such light is known as spill light. It reduces the beneficial use of light because light which otherwise could be useful at the target area, and which is produced by the fixture, does not end up in the target area.
Additionally, even though such fixtures produce a relatively controlled, concentrated beam, the nature of light is such that even such a beam cannot be precisely collimated to long distances and therefore there is some beam spread and dispersion of light. It is therefore difficult to achieve sharp cutoff of the beam pattern from each of the fixtures at long distances and difficult to control the precise shape and other characteristics of the light. It is difficult to match the shape of the light from the fixture with the shape of the target area.
U.S. Pat. Nos. 5,343,374 and 5,337,221 show and describe apparatus and methods which address light control problems. Their preferred embodiments utilize a light fixture which can be, but is not required to be, a bowl-shaped reflector, a primary reflector, and an on-axis arc lamp. The light fixture is directed away from the target area into a mirror or secondary reflector. The mirror redirects at least a portion of the light from the primary light source. The nature of the combination is such that it produces a controlled beam with sharp precise cutoffs. Therefore, at a race car track as an example, these fixtures can be placed on the ground. Each fixture directs a light beam so that it covers the width of the track and yet cuts off at the top or very close to the top edge of the restraining wall of the outer edge of the track. The light is therefore placed on the track instead of off the track. It also is kept out of spectators' eyes. A plurality of such fixtures can be placed around the interior of the track and coordinated to produce even, uniform but controlled lighting for the track.
Although such systems do have efficiencies, there is still room for improvement regarding such devices and methods.
For example, the size of such apparatus is substantial. In the preferred embodiment described in U.S. Pat. Nos. 5,337,221 and 5,343,374, the light producing fixtures are essentially the same size as conventional bowl-shaped fixtures with on-axis arc lamps. For example, the reflector can be several feet in diameter at its face. The mirrors or secondary reflectors can be on the order of several feet tall by several feet wide and are spaced several feet from the light producing fixtures.
Additionally, those types of arrangements introduce difficulties regarding efficient utilization of light. All of the light from the light producing fixture may not be redirected by the secondary reflector or mirror. For example, some light from the light producing fixtures may fall outside the mirror and therefore be lost.
Also, the flexibility of these arrangements in terms of ease of positioning and adjustability is limited.
It is therefore the principle object of the present invention to provide a high efficiency, highly controllable light fixture and method which improves upon the state of the art.
A further object of the present invention is to provide an apparatus and method which efficiently utilizes light.
Another object of the present invention is to provide a highly controllable light for large areas from a relatively compact fixture.
Another object of the present invention is to provide flexibility with regard to operational characteristics such as adjustability of the characteristics of the light produced.
Another object of the present invention is to provide flexibility with regard to directing light to a target area.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.